To calculate the absolute deviation of a data point from the mean, you need to follow these steps:
Find the mean (average) of the data set.
Subtract the mean from the data point.
Take the absolute value of the difference obtained in step 2.
Let's calculate the absolute deviation of 23 from the given data set:
Mean = (5 + 11 + 21 + 23) / 4 = 15
Difference = 23 - 15 = 8
Absolute value of the difference = |8| = 8
Therefore, the absolute deviation of 23 from the data set {5, 11, 21, 23} is 8.